Cathode Ray Tubes: Understanding the Role of Cathodes

In summary, a cathode is defined as an electrode where conventional current flows out of it or electrons flow into it, while an anode is where conventional current flows into it or electrons flow out of it. However, in a Cathode Ray Tube, the electrode that emits streams of electrons is classified as the cathode, which may seem contradictory. This is because the terms cathode and anode refer to the function of the device rather than conventional current flow. In this case, electrons are still flowing out of the cathode.
  • #1
marcmcgee
2
0
From my current understanding, a cathode is an electrode which has conventional current flowing OUT of it (or electrons flowing INTO it) while an anode had conventional current flowing INTO it (or electrons flowing OUT of it). From this definition, I don't understand why the electrode which emits cathode rays (which I understand to be streams of electrons) in a Cathode Ray Tube is classified at the cathode. Why is it classified as the cathode if it allows electrons to from it to the other electrode?

Cheers,
Marc
 
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  • #2
Cathode and anode refer not to conventional current flow but to the function of the device.

Electrons are flowing out of the cathode.
 
  • #3
Thanks for the reply, appreciate it.
 

1. What is a cathode ray tube (CRT)?

A cathode ray tube is a vacuum tube used in older television and computer monitors. It contains an electron gun, a cathode, and an anode, and works by creating a beam of electrons that is directed towards a screen coated with phosphors, creating the images we see on the screen.

2. What is the function of the cathode in a CRT?

The cathode in a CRT is responsible for emitting a stream of electrons, also known as a cathode ray. This stream of electrons is then accelerated and focused by the anode, creating the images on the screen.

3. How does a CRT produce images?

A CRT produces images by using the electron gun to create a beam of electrons that is directed towards the screen. The screen is coated with tiny phosphors that emit light when struck by the electrons, creating the pixels that make up the image.

4. Why are cathodes made of materials such as tungsten or nickel?

Cathodes in CRTs are typically made of materials such as tungsten or nickel because these metals have a high melting point and can withstand the high temperatures and electric currents required for the cathode to emit electrons consistently.

5. What is the lifespan of a cathode in a CRT?

The lifespan of a cathode in a CRT can vary depending on usage, but on average it can last for several thousand hours before needing to be replaced. However, with the advancement of technology, CRTs are being replaced by newer display technologies with longer lifespans and higher resolutions.

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